Topic: km140 > ps2 > r-09hr

[soomlos]

What's wrong with this combination?

I'm trying to run neumann skm140s > denecke ps2 > edirol r09hr line in.
All I'm getting is an extremely low, distorted, underwater sounding signal. Get the same results running mic in too, just a little bit louder.

All the gear is operating fine by itself when connected to other equipment.

If I substitute at853's for the mics I get a nice sounding signal.
Am I missing something obvious? 

[DSatz]

Your recorder has unbalanced inputs. The outputs of the microphones are balanced, which means that you are connecting only two of the three wires coming from the microphones to the recorder.

It so happens that this series of Neumann microphones places the output signal on pin 3 (in inverse polarity), with pin 2 being a passive terminal and pin 1 being ground. You are probably trying to take the signal from pin 2 and your cable quite possibly is connecting pin 3 to pin 1--so all you're getting is a tiny bit of leakage.

I keep trying to explain this to people here, but they don't believe me. You and others have nicely proved my point by example, yet I know that I'll still get arguments from people who should know better. So I'll say it one more time: No one way of connecting the balanced signal from a professional microphone to the unbalanced input of consumer recording equipment can possibly work for all microphone types. There IS NO SUCH THING as a "balanced to unbalanced adapter" that works with all (or even most) balanced microphones.

Pin 1 on the XLR output of a microphone is always shield/ground--but the either pin 2 or pin 3 may be driven by the microphone's circuitry while the other pin may not be. (Many microphones that have balanced outputs don't have both signal leads actively driven; Neumann transformerless microphones are a good example. Choose the non-driven output pin and you get almost no signal at all.) Then whether you need to ground the remaining lead or leave it completely unconnected will depend entirely on the design of the microphone. Make the wrong choice there and you either will get very little signal, or risk clipping or even damaging the microphone, not to mention the power supply issues.

Neumann's instruction manual is very clear about how to connect a KM 100-series microphone to an unbalanced input. Your adapters (from the outputs of the PS-2 to the inputs of your recorder) need to be rewired to follow those instructions. Then you will still need differently wired adapters for your other types of microphone.

--best regards

P.S. added the Sunday morning after: Actually what I shouted above was a little too restrictive; a preamp that has audio input transformers will work with unbalanced or balanced microphones. But good input transformers are expensive and not exactly small (conversely, the small, inexpensive ones aren't very good). So I hesitate to recommend transformers without further discussion, though some people use them in exactly this situation.

[soomlos]

Thanks for the quick response.
I had read in another thread you mention this problem, but thanks for providing greater clarification here.

I was planning on having a custom adapter cable made so will keep this in mind when doing that...

Thanks again

[DSatz]

soomlos, if you don't have the instruction manual for the microphones, you can download it as a PDF from www.neumann.com. I really recommend that you read the section of the manual which explains how to connect KM 100-series microphone to unbalanced inputs, and whoever is wiring up your adapters should read it also.

I've seen far too many people, including (relative) experts, make wrong assumptions about how this should be done. The most basic mistake is to assume that the approach that works for one type of microphone will work for any other; it ain't necessarily so.

Just to show how extreme it can get: Neumann sells two different amplifiers ("output modules" or bodies) for this series--the standard one, and one with reduced low frequency response, the "KM 100 F". The balanced-to-unbalanced wiring scheme that works for the standard KM 100 won't work for the KM 100 F, nor vice versa. So not only within the same manufacturer's catalog, but even within the same series of microphone, that kind of difference can exist. You would need differently wired adapters for each.

There are standards for professional microphones and there are standards for consumer hi-fi-type equipment. Each set of standards is based on the premise that equipment of all one type or the other is being connected together. Nothing in either set of standards says anything about how equipment from one category should be connected to equipment from the other category--and that's what you're doing here.

--best regards

[Gordon]

my suggestion would be to get a actual preamp.  the mics are the most important part but a nice pre behind it can make a world of difference. 

[DSatz]

Of course, a preamp with balanced microphone inputs and proper phantom powering would take care of the problem nicely--though I can well understand that someone who's already bought a nice power supply such as the PS-2 may not be so eager to make that investment redundant.

On the plus side, a suitable preamp might improve the dynamic range of this person's recordings. A lot depends on the sound levels being picked up by the microphones--but even highly sensitive professional condenser microphones don't often put out signal levels at quite as high a voltage as line inputs of a recorder "expect."

There's usually about a 30 - 40 dB gap between consumer mike level and line level, and the output levels of professional condenser microphones are often just above the midpoint of that range. You often can't connect them to the mike inputs at all without an attenuator ("pad"), or else the signals from the microphones will simply overwhelm and overload the mike input circuitry, causing severe distortion.

But if you connect the microphones to the line inputs, you may have to turn up the "record level" controls on the recorder so high that the input noise (inherent or "self" noise) of the line inputs is audible in the recording. Again this all depends on the particulars of the equipment and the sound levels of whatever you're recording, as well as how loud you play back the finished recording, so YMMV rather widely.

[soomlos]

OK, I just downloaded the product manual from neumann.com.. Thanks

I agree it's much better to have a preamp between mics and recorder, I have a v3 and denecke ad20.
The only reason for trying to get this smaller combo to work is for the rare times when the v3 is just too big to carry. The ps2/ad20 combo has worked well in those circumstances, but it's only 16/44.1.

Thinking now maybe I should get something like the mp2 or mixpre for a smaller 24bit setup...
km140's>mp2>r-09hr.

[DSatz]

> The ps2/ad20 combo has worked well in those circumstances, but it's only 16/44.1.

No, actually the AD-20 has a 20-bit A/D converter--thus its name. I just verified this by experiment; the unit really does put out a 20-bit S/P-DIF data stream.

I recorded around 15 seconds of a 400 Hz sinusoid through one channel of a "Zefiro InBox"--the original version of what is now known as the Denecke AD-20. Here are the first few sample data values in hexadecimal:

00  e6  c8
80  4a  c3
70  d2  bd
80  95  b8
90  88  b3
70  b3  ae
70  28  aa
80  01  a6
d0  f6  a1
10  5e  9e
...

These are in "little-endian" (Intel) sequence, so the first byte (two hex digits) of each sample is the lowest-order byte. Its lower "hex digit" is always 0, representing the four lowest-order bits out of 24--those are being "left blank." But the upper four bits are significant--you can see that they're constantly changing.

So you are already better off than you may have realized. Of course the actual dynamic range of the signal is limited by the noise levels of the recording environment, the microphones and the analog circuitry of the AD-20--but that's equally true for any other preamp and converter in the real world, or (with all due respect to John Willett of Sennheiser/Neumann) even a "digital microphone" system.

--best regards

[soomlos]

updating this thread with confirmation that the cable used to connect neumann km100's>denecke ps2>edirol r-09hr needs to be rewired making pin 3 hot. Tried the new cable out last night at a moderately loud rock concert and got good results with peaks at -12db running line-in and edirol set to 70.

Thanks DSatz for the help and suggestions!

[F.O.Bean]

updating this thread with confirmation that the cable used to connect neumann km100's>denecke ps2>edirol r-09hr needs to be rewired making pin 3 hot. Tried the new cable out last night at a moderately loud rock concert and got good results with peaks at -12db running line-in and edirol set to 70.

Thanks DSatz for the help and suggestions!

thats kind of low for 16-bit tho. as always, YMMV

[Sunday Driver]

updating this thread with confirmation that the cable used to connect neumann km100's>denecke ps2>edirol r-09hr needs to be rewired making pin 3 hot. Tried the new cable out last night at a moderately loud rock concert and got good results with peaks at -12db running line-in and edirol set to 70.

Thanks DSatz for the help and suggestions!

That sounds like a little more gain loss than what I lose running Audio Technica U853-Cs > PS-2 > Edirol R-09HR (line in). I always end up running at about 65/66 for the gain level at moderately loud shows. I was expecting the gain loss when I purchased this gear orginally though. The noise floor on the R-09HR is so low at 24bit though that you can boost it to normal levels without "destroying" it. I am in the market for a preamp though.

[twoodruff]

updating this thread with confirmation that the cable used to connect neumann km100's>denecke ps2>edirol r-09hr needs to be rewired making pin 3 hot. Tried the new cable out last night at a moderately loud rock concert and got good results with peaks at -12db running line-in and edirol set to 70.

Thanks DSatz for the help and suggestions!

thats kind of low for 16-bit tho. as always, YMMV

the edirol is 24 bit correct?

[F.O.Bean]

updating this thread with confirmation that the cable used to connect neumann km100's>denecke ps2>edirol r-09hr needs to be rewired making pin 3 hot. Tried the new cable out last night at a moderately loud rock concert and got good results with peaks at -12db running line-in and edirol set to 70.

Thanks DSatz for the help and suggestions!

thats kind of low for 16-bit tho. as always, YMMV

the edirol is 24 bit correct?

ahhh, you are correct Trey. Nevermind